There is a plugin for GIMP (a open source Adobe PS basically) that adds a lot of DX compression based export modes and plus can create mipmaps. I think I converted mine to DXT5 or DXT3 upon export they are fairly similar in terms of image quality and file size. I think 1k texture sizes or 768x768 is a reasonable size. I chose 2K just to use for demonstration purposes. Most textures are 256x256 or 512x512 by default.
Here's two tools you might find useful DZoneConverter_1.3 & EverQuest Zone Viewer.
EverQuest Zone Viewer you might find useful you can view zones and texture with it from a s3D file it's quicker than loading the game plus with it you can walk through walls so a real good way to test and look at zones your texture editing.
https://drive.google.com/open?id=0B1...ERhUkxfTmlSRDA
DZoneConverter_1.3 you can export files from a s3d file like .OBJ model files which can be imported into a 3D program like Blender.
http://sourceforge.net/projects/eqem...se_mirror=osdn
Here's a little example of a froglok model exported with DZoneConverter_1.3 into Blender I played around with a little I didn't actually UV texture map it just used a texture material. I also used some of the tools to distort/reshape the model itself it in different ways a little too. If these were player designed models with animations a tool like this and program like Blender would allow for a lot manipulation of it clearly 3Dmodeling is quite awesome stuff.
http://www.eqemulator.org/forums/showthread.php?t=38310
Anyway have fun on 2. Give a Everquest Zone Viewer a try it's a lot better and quicker than loading the actual game client way more efficient for texture editing. Great texture swaps btw I looks like you tried to keep relatively similar natural to the original look, but with higher resolution image quality of course.